Why You Need a Trusted Advisor

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I’ve providing advisory services to a Fortune 500 organization for a few months now. As all large organizations, they adopted Power BI Premium. However, they have provisioned only one Power BI Premium P1 node which has been showing signs for overutilization. In the process, I discovered they have purchased 40 Power BI Premium cores with 32 cores left unutilized! In other words, they used 1/5 of what they’ve been paying Microsoft as Power BI Premium fees. How did they arrive at this unfortunate situation?

A year or so ago, they used the Power BI Premium Calculator to estimate the licensing cost on their own. They plugged in 10,000 users and got a recommendation for 5 P1 nodes (or 40 cores). And that’s what they bought, assuming that they will get a cluster of five P1 nodes that would load balance the reports across nodes. When they set up Power BI Premium, they set up only one P1 capacity and all the important reports got in there. And these reports have been running just fine for a long time with thousands of users … The other 32 cores – sitting ducks.

Power BI Premium doesn’t currently load balance across nodes. Once you’ve licensed a certain number of cores, it does give you the flexibility to provision nodes of different sizes. So, with 40 licensed cores, you can set up 5 P1 nodes, or 2 P2 nodes and 1 P1 node, or one P3 node and 1 P1 node. Unfortunately, the flexibility ends there. Once you provision the capacity, the meter is running use it or not. And if you’re not using all these licensed cores, you still pay unless you manually scale down the capacity. I hope to see Power BI Premium Serverless sometimes in the future, where the service scales up and down on demand and you pay for what you really consume. This will void the decision on how much capacity and nodes you need, probably save you lots of money, and make Power BI Premium more affordable.

The moral of this story? Hire a trusted advisor and technology expert, and save a lot!

Conquering Time Zones

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A client has Power BI models connected to Dynamics Online. Dynamics stores all dates in UTC instead of keeping the time offset, such as 7/14/2020 1:21:29 AM +00:00. Naturally, the users want to see dates localized to the US Eastern Time zone. Easy, right? Use the Power Query ToLocal time transformation (in the Transform ribbon, expand Time, and then click To Local) to offset with the desired number of hours. But there are a few issues with this approach:

  1. It will work fine in Power BI Desktop (assuming you are on the Eastern Time zone because Power BI will pick your computer settings), but it won’t work when you publish the dataset to powerbi.com. The reason for this is that Microsoft sets the time zone of Azure servers to UTC irrespective of the geo location of the Power BI data center. So, when Power BI Service refreshes the dataset, it will convert dates to its local time (UTC) and the net effect is that the date remains unchanged.
  2. You can attempt using the M DateTimeZone.SwitchZone function but for some obscure reason, casting the column data type to Date after the zone change puts the date back to UTC.
  3. The hour offset changes depending on when the country switches to Daylight Saving Time.

When the going gets though, the developer writes some code which in this case would be a Power Query ToTimeZone query function.

# open a Power Query blank query in Advanced Query mode and paste the code. Then rename the query to ToTimeZone
let
 Source = (UTCTime, TimeOffset) =>
let
 CurrentYear = Date.Year(DateTime.FixedLocalNow()),
 DST_Start = Date.StartOfWeek(#datetimezone(CurrentYear,3,14,0,0,0,TimeOffset,0),Day.Sunday) + #duration(0,2,0,0),
 DST_End = Date.StartOfWeek(#datetimezone(CurrentYear,11,7,0,0,0,TimeOffset+1,0),Day.Sunday) + #duration(0,2,0,0),
 OffsetTime = if UTCTime >= DST_Start and UTCTime < DST_End then TimeOffset + 1 else TimeOffset,
 #"Change Time" = if UTCTime=null then null else DateTimeZone.RemoveZone(UTCTime) + #duration(0, AdjustDST, 0, 0)
in
 #"Change Time"
in
 Source

The function takes two arguments: UTCTime and TimeOffset. For each row, the source query will pass the date as of datetimezone data type. The TimeOffset is the default time offset outside Daylight Saving Time. So, for US Eastern time zone, the time offset will be -5. Notice that I don’t specify types for the arguments because you may have empty (null) dates. If null is passed to UTCTime, you’ll get a runtime error. Instead, the last line checks if the incoming date is null. The function adjusts the time offset during Daylight Saving Time. Finally, it removes the time zone from the original date, so we get the date in a datetime format and then adds the offset. So, 7/14/2020 1:21:29 AM +00:00 will become 7/13/2020 9:21:29 PM.

Once the ToTimeZone function is ready, we can call it from the source query, like so:

let
 Source = OData.Feed("https://<tenant>.crm.dynamics.com/api/data/v9.1/appointments ", null, [Implementation="2.0"]),
 ToLocalTimeZone = Table.TransformColumns(Source, {{"createdon", each ToTimeZone(_, -5)}, {"scheduledstart", each ToTimeZone(_, -5)}}),
 #"Changed Type" = Table.TransformColumnTypes(ToLocalTimeZone,{{"createdon", type date}})
in
 #"Changed Type"

Notice that I use the TransformColumn transformation so that I can convert multiple date columns in one line and don’t end up with additional custom columns. In other words, I’m updating the date columns in place. Finally, I change the data type to date so that I can join to a Date dimension.

You can easily extend this code to handle times in multiple time zones, such as to report the time depending on the geo location of the user who entered the data. This will require storing the user time zone, such as in the Dynamics systemusers table.

Designing Responsive Power BI Reports (Part 2)

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In my previous post about responsive reports, I said that changes to the report design can dramatically reduce the report load time. But you will undoubtedly reach a point where you cannot optimize the report any further. After all, having a page with a single visual might be fast, but I doubt it would deliver much business value. What else can be done to speed up the reports and ideally achieve a page load time of a few seconds? Our next stop for that project is to revisit the solution architecture. The client initially opted for a hybrid architecture where the reports use live connection to on-prem SSAS Tabular models. However, a significant time was spent in Power BI showing “loading data” before rendering the report. What took so long?

In this case, Power BI was hosted in the Azure West region, the Tabular server in the company data center in Atlanta, and most users were in the East region. This resulted in round trips crossing the country for each visual.

  1. A user in the East region requests a report which is hosted in the West region.
  2. Each visual generates a query which is sent to Tabular in the company data center.
  3. SSAS returns data back to the West region.
  4. Report payload is sent to the user in the East region.

Ideally, users, reports, and data should be in the same region. However, a long-standing limitation of Power BI is that once the first user signs up for Power BI, Power BI determines the data region based the user location and you can’t move it unless you open a support ticket with Microsoft. Power BI Premium will let you create premium capacities in a different region, but by default these capacities will be created in the original Power BI region and you can’t change the region once the capacity is created either. The chart below shows the round-trip latency doubles if the user is in the East region, but Power BI is in the West.

We decided to move the semantic model to Power BI so that Power BI owns the data. Besides potentially improving the report load time, this architecture has also other important advantages (to learn more, read my “Power BI Large Datasets: The Good, the Bad, and the Ugly” post). If you’re not on Power BI Premium, that “movement” might not easy if you have opted to use Visual Studio or Tabular Editor for development. That’s because Power BI Pro doesn’t expose the XMLA endpoint, so your only option is to migrate the model to Power BI Desktop. But migrating an SSAS Tabular project to Power BI Desktop is not officially supported and there is no automatic migration path.

Thanks to the enhanced dataset metadata (a better name would have been “metadata done right this time”), you could opt for cracking the Power BI Desktop file and replacing the model schema (my “Power BI Source Control” blog has the steps to get to the schema). You might get lucky especially if your Tabular project uses structured data source (the only data source type supported by Power BI Desktop). However, if it uses legacy data sources, you must change every table to use a structured data source and making changes to the JSON schema by hand and Power BI Desktop refusing the load the model with every typo is no fun.

On the other hand, Power BI Premium lets you deploy the SSAS model to the workspace XMLA endpoint. The prerequisites are:

  1. Upgrade the Tabular model in Visual Studio to 1500 compatibility mode. This adds special annotations to the data source. If you don’t upgrade to 1500, you’ll find that you won’t be able to schedule the dataset for refresh as Power BI Service won’t show any connections.
  2. Enable the XMLA endpoint for read-write in the capacity settings.
  3. Enable the “Export data” tenant setting in Power BI (to learn more about this setting, read my “A False Sense of Security” blog).
  4. Like the “Export data” battle wasn’t enough, we found that we have to beg the Security group to enable also the “Analyze in Excel with on-premise datasets” tenant setting. I have no idea what this setting has to do with the XMLA endpoint. Luckily, Fidler showed us the exact error message that this setting must be enabled.
  5. In Visual Studio, change the model processing option to “Do not process”. The “Troubleshoot XMLA endpoint connectivity” article has the details.

Moving the semantic model paid big dividends. We could only see “loading data” for a moment. We also found that the network speed of the user connection and the browser play a significant role. For best performance, users should use Chrome or new Edge and have a broadband connection. We were able to reduce further the load time of the first page by enabling the published dataset for query caching which is only available in Power BI Premium.

Propagating DAX BLANK() Over Relationships

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Happy 4th of July with a DAX puzzle!

Consider the following three tables. Notice that InvoiceDetails has a data integrity issue where the third row doesn’t have InvoiceNo (InvoiceNo is blank).

What would a measure with COUNTROWS(Invoice) return for Teo? BLANK(), right? And that’s correct because Teo has no invoices. Now, what would COUNTROWS(InvoiceDetails) return for Teo? BLANK() again given that Teo has no line items? Nope, it returns 1. In other words, it will return the count of all line items whose InvoiceNo is blank. How come?

COUNTROWS(Invoice) returns blank for all customers with no matching rows in Invoice because these customers are mapped to the blank row in Invoice, which is excluded from COUNTROWS by default. But if you change COUNTROWS(Invoice) to COUNTROWS(VALUES(Invoice)), then 1 will be returned for these customers. Then, the filter flows to InvoiceDetals through the blank row and counts all rows with blank InvoiceNo.

This behavior wouldn’t have happened in SQL. However, DAX blank is not SQL null. Blank sales in DAX means no sales or zero sales, but null sales in SQL means unknown sales. Therefore, in DAX blank = blank, but in SQL null is always different than null.

Thanks to the Father of DAX, Jeffrey Wang, for shedding light in dark places.

Atlanta MS BI and Power BI Group Meeting on July 6th

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MS BI fans, please join us online for the next Atlanta MS BI and Power BI Group meeting on Monday, July 6th, at 6:30 PM. David Eldersveld, a Microsoft MVP, will demonstrate cool visualization techniques using DAX. For more details, visit our group page and don’t forget to RSVP (fill in the RSVP survey if you’re planning to attend).

Presentation:DAX Visualization Techniques for the Power BI Table/Matrix
Date:July 6th, 2020
Time6:30 – 8:30 PM ET
Place:Join Microsoft Teams Meeting

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Computer audio is recommended

Overview:Did you know that DAX is more than a modeling language and can also be used for data visualization? From sparklines to bullet charts, Unicode text to SVG, icons to maps; learn different techniques to build visuals within visuals using DAX. In this session, David Eldersveld guides you through techniques that go beyond basic conditional formatting to enhance your table and matrix visuals.
Speaker:David is a Solution Architect and Microsoft MVP who has employed skills in technology development, data integration, data analysis, and Microsoft BI for over ten years. David enjoys building BI and analytics solutions with technologies in Microsoft Azure and the Power Platform. In addition to his work with the Microsoft Data Platform at BlueGranite, he also blog at dataveld.com.
Prototypes without pizza:Power BI latest features

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A False Sense of Data Security

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UPDATE 11/26/2020: After the latest update to tenant settings, I’m glad that the new “Export to …” settings don’t affect external connections anymore. There is now a new setting “Allow live connections” to control external connectivity. Read “Updated Export Settings” to learn more.

The Power BI “Export data” setting is horrible. I wish Microsoft never came up with it and no other Microsoft tool has it. Apparently, the premise here is to prevent users from exporting data behind the report so it does not end up in wrong hands. But all it accomplishes is a false sense of data security and does more damage than good. Like users can’t take screenshots and share them wherever they please. Or print and mail reports. Unless of course, you disable printing reports too, but where is that path of not trusting your users going? Why don’t you just disallow them from viewing reports at all? “No data, no problem”, right?

Besides “exporting” data, this setting effectively disables all external connections to published datasets. Therefore, the following Power BI features won’t work:

  1. Creating reports from published datasets, which is a best practice.
  2. Publishing semantic models from Visual Studio via the Power BI Premium XMLA endpoint. Even if you enable the XMLA endpoint for read/write, “Export data” will overwrite it because it’s highest level overwrite
  3. Connecting other tools to published datasets, such as SSMS, Tabular Editor, DAX Studio, Profiler, and third-party reporting tools.
  4. Using the “Analyze in Excel” feature for creating Excel reports connected to published datasets.

So, leave “Export data” enabled. If you really want to prevent sensitive data outside your organization, consider applying sensitivity labels which integrate with Office 365 information protection.

A Gateway to Hell

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“Life is suffering and suffering is unavoidable”. Buddha must have dealt with data gateways. Two “gotchas” that surfaced recently after countless hours of troubleshooting:

  1. A bug in the data gateway AD lookup cache – In my “Gateway AD Lookups” post, I described a very useful gateway feature to look up the on-prem user identity from a cloud identity so that you don’t have to create explicit mappings. The gateway maintains an internal dictionary cache so that it doesn’t have to look up Windows Active Directory for every query. This cache can’t be disabled. The issue is that If you have an older gateway build, e.g. December 2019, there is a bug (and a security vulnerability) with concurrent access to cache which may cause the gateway to map the interactive user to a wrong AD user under heavy load. The issue was fixed in a later build, but the fix introduced another issue by imposing a very coarse lock (probably the entire cache) which may reduce concurrency with many users running reports. In other words, under a heavy load user requests queue up to wait for the cache lock to be released. This issue will be fixed in the next July 2020 gateway build.
  2. Beware stale data sources registered in the gateway – Now that we’ve addressed the concurrency bug, the same client reported a new issue where every hour or so users can’t render reports connected to the gateway for a couple of minutes and then the issue resolves itself. The culprit turned out to be neglected Analysis Services data sources registered in the gateway. By default, Power BI dashboards will query these connections every hour to cache tile data (the frequency can be changed on the dataset settings page, but it can’t be disabled). The problem was that the master account used to connect to Analysis Services changed its password. While the team updated the connections in the actively used data sources, it did not do so for the neglected data sources (no one is using them, right?). However, the dashboards still submit queries to update the tile cache and the gateway asks AD to authenticate the master account.  Then, the domain controller locks the master account for a few minutes after a certain number of attempts since it rejects the logon attempt with the old password. The solution was to remove unused data sources from the gateway.

Designing Responsive Power BI Reports

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I’m currently providing advisory services to an enterprise client for architecting and implementing an executive dashboard. As a typical dashboard, the UX design included various KPIs that look like these:

The Power BI report implementation followed the design and the above visualization was implemented as four cards and two textboxes. Including other UX elements, such as icons, labels, etc., the most important summary page of the report ended up having more than 100 visuals. It took 25 seconds to render the page on average, which is horrible performance. Performance Analyzer showed that DAX queries are very fast and most of the time was spent in the “Other” category. This means that because JavaScript is single-threaded, visual rendering is sequential. Indeed, the SQL Server Profiler revealed that out of 25 seconds, the first 15 seconds were spent elsewhere before Analysis Services Tabular starts receiving DAX queries. The Performance Analyzer document provides the essential coverage about how Power BI renders visuals, but the bottom line is this:

The more visuals the page has, the slower it will be. If you find that most of the time is spent in the “Other” category on page refresh, more than likely this is caused by Power BI serializing the visual rendering. If this is the case, the best course of action would be to reduce the number of visuals.

For example, the above visualization can be rendered with one visual only (Matrix) and some blackbelt visualization techniques. Matrix supports rendering measures on rows (in the Values section of the Format tab, turn on “Show on rows”). Spacing the rows can be achieved by increasing row padding. And icons can be rendered with conditional formatting. Another technique for reducing visuals and faster rendering is eliminating many labels with a page background image. What didn’t help was disabling visual interactions although it doesn’t hurt disabling it if you don’t need it. We’ve also found that browsers differ in how fast their render visuals. Internet Explorer was the slowest while Chrome and the new Edge were the fastest.

How fast did their report get after applying such optimizations? Between 50 and 60% faster.

True, Power BI has report design limitations. Developers with SSRS background will miss more advanced features, such as nesting visuals (e.g. bullet graph inside a matrix) and asymmetrical crosstab layouts. Still, techniques as the one I shared above will help you create more responsive reports.

Links to Power BI Mobile Reports or Apps

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You have deployed your Power BI reports/apps and now management is eager to use them. But how do you provide an easy one-tap shortcut for them to launch a specific report or app on mobile devices and open them in Power BI Mobile? For example, in a recent project, we had to provide executives with an easy “button” to see their executive dashboard on iPhone/iPad. To make things more interesting, the ask was to auto-provision “the button” so the users don’t have to create it manually.

Each approach has specifics controlled by the operating system on the device. Your best option will probably be Siri or Android shortcuts.

  1. Siri or Android shortcuts – Use this option when you want the user to initiate the link either by clicking on it or by speaking the associated phrase. For more information, read “Using Siri Shortcuts in Power BI Mobile iOS App” and “Use Android app Shortcuts in the Power BI Android app” The downside of this approach is that Apple doesn’t currently have shortcut APIs so you can’t provision the shortcuts, such as by using Microsoft Intune or AirWatch. In other words, the user must manually create the shortcut within Power BI Mobile. However, they can send the shortcut to other users as “untrusted shortcut”.
  2. Redirect links – Use this option when you want the device to prompt the user to install the app if it is not already installed. For more information, read “Create a link to a specific location in the Power BI mobile apps“. The steps to create a shortcut are device specific. In this project, the client used AirWatch to provision “weblink/webclip” icons to launch the redirect links. The caveat for using redirect links is that the user will be always prompted to “close” the prompt or open the app, and as far as I know, there is no way to bypass this prompt.
  3. Universal links – Luckily, Power BI supports iOS universal links. Just navigate to the report in the browser, copy the link, and associate it with an icon. The old way to create the link, which is still supported, was to use the mspbi scheme, such as mspbi://app/OpenReport?appId=1f3d811e-8d6c-4708-9034-ad5c2db1615b&reportObjectId=16c484cd-d2b2-40ab-bddc-3cb97b62e518. Choose this option when you want to bypass the prompt asking the user to open the app. Universal links work if the link is in email message, Siri shortcut or some other app, such as Notes. The downside is that if the user creates a “weblink/webclip” shortcut with the link using the “Add to Home screen” feature or auto-provision with AirWatch, the shortcut will always open in the browser and bypass Power BI Mobile. In other words, the link won’t work when launched from a “weblink/webclip” shortcut.

Let’s summarize the three approaches.

OptionProsCons
Siri or Android shortcuts

(Recommended)

No prompt, can be voice activatedSince there are no APIs to work with shortcuts, they can’t be automatically provisioned
Redirect “deep” linksAsk the user to install the app if not presentAlways prompts the user to “close” or open Power BI Mobile.
Universal linksDon’t prompt the userDon’t work from “weblink/webclip” shortcuts

Atlanta MS BI and Power BI Group Meeting on June 1st

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MS BI fans, please join us online for the next Atlanta MS BI and Power BI Group meeting on Monday, June 1st, at 6:30 PM. Stacey Jones, a Principal Data Solutions Architect at the Atlanta Microsoft Technology Center, will introduce you to Microsoft Cognitive Services and show you how to integrate it with Power BI. For more details, visit our group page and don’t forget to RSVP (fill in the RSVP survey if you’re planning to attend).

Presentation:AI + BI = Easier paths to Insights & Action
Date:Monday, June 1st, 2020
Time6:30 – 8:30 PM ET
Place:Join Microsoft Teams Meeting

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Computer audio is recommended

Conference bridge (toll) number 1 605 475 4300, Access Code: 208547

Overview:Have you ever wondered how to leverage AI in your Reports? In this presentation, I will show you how to use Azure Cognitive Services in Power BI to accomplish things like detecting the language of a given passage of text, translate that same text into another language, detected the sentiment of the text and more. The possibilities are endless with these techniques, you could use it to assess your companies brand image, analyze what your customers are saying about your company on social media, and many others. No data scientist required!
Speaker:Stacey Jones specializes in mentoring and guiding firms in their efforts to build a modern Data, AI & BI governance programs that empower their business with Self-Service BI and Data Science capabilities. He currently serves as the Principal Data Solutions Architect at the Atlanta Microsoft Technology Center (MTC).
Prototypes without pizza:“Power BI latest features” by Teo Lachev

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